Method of rupturing walls



July 27, 1965 e. FRANCIS ETAL METHOD OF RUPTURING WALLS Filed June 6,1962 INVENTOR. GUS FRANCIS JAMES A DUNN ATT RNEY United States Patent3,196,791 METHOD OF RUPTURING WALLS Gus Francis, 1480 S. Josephine,Denver 10, Colo., and James A. Dunn, Lakewood, Colo.; said Dunn assignorto said Francis Filed June 6, 1962, Ser. No. 200,379 Claims. (Cl. 10223)This application is a continuation-in-part of our application Serial No.145,709 filed October 17, 1961, entitled Wafer Destruct Charge.

This invention relates to a method and apparatus for directionallypropelling projectiles by means of explosives without the aid of aprojection chamber.

The present invention is principally concerned with the use ofexplosively propelled metal projectiles for simultaneously rupturingfuel tanks of missiles and destroying boosters and other mechanism ofspace vehicles and other jet propelled devices, for the purpose ofself-destructing the devices when they are off-course and have assumederatic and uncontrolled paths of travel. The invention will be describedand illustrated principally in connection with this application but itis by no means limited thereto.

It is now standard practice to incorporate self-destruct devices inmissiles and in propelling devices for spacecraft to provide forautomatic self-destructof the device when it is off-course. Ordinarily,self-destruct devices rupture fuel tanks which results in destruction ofthe missile either through loss of pressure in the fuel tank, loss offuel, explosions, or for other reasons. In the case of missiles fueledwith hypergolic propellants wherein fuel and oxidizer are carried inseparate tanks, selfdestruct is achieved by simultaneously rupturingboth tanks to permit the fuel and oxidizer to come together and igniteso that the resultant violent reaction rips the missile apart,terminating the mission.

Achieving self-destruct by causing structural damage to tanks or partsof missiles is ordinarily accomplished with explosive bombs or shapedcharges. Bombs or shaped charges are placed against the outside fueltank wall-s, against domes of fuel tanks, or upon the guidancemechanism.

This method of achieveing self-destruct is subject to a number ofdisadvantages. The damage to missile parts must be directional andspecified and if two tanks containing hypergolic fluids are to beruptured, rupturing of both tanks must be accomplished substantiallysimultaneously. When bombs are used, the fragmentation of the metal caseis random and fragment particle sizes vary so that it is diificult toprecisely control the direction of particles with accuracy to achievedestruction in the specified areas.

When linear shaped charges are used, damage is greatest when standoffdistances are exact and predetermined and this is not always possible ofattainment. Shaped charges are more effective in penetrating thickmasses of material and causing damage within a narrow specified radialdiameter. When used against targets which require a wide area to bedestructed, shaped charges are ineffective. Even when bombs or shapedcharges can be placed against the outside tank walls, against domes, orupon the guidance mechanisms, failures often result in propagation ofthe shock wave due to sharp bends or poor contact between joiningstrands.

' Now that missiles and space vehicles are traveling outside theatmosphere where the creation of shock waves by explosives is no longerpossible, the use of explosive devices is further limited. For example,when bombs are used to rupture domes of propellant tanks in theatmosphere, the failure of the domes is caused principally by air blastwaves since fragmentation is random and uncontrollable. Obviously, sinceit is impossible to form ice shock waves in outer space this method ofdestruction cannot be used there.

It therefore is an object of this invention to provide a method andapparatus for directionally and accurately propelling projectileswithout the use of a propelling chamber.

It is another object of this invention to provide a method foraccomplishing self-destruct of jet propelled missiles.

It is still another object of this invention to provide a method andapparatus for simultaneously rupturing a plurality of missile fuel tanksfor the purpose of selfdestructing a missile, and

It is a further object of this invention to provide a method andapparatus for accomplishing self-destruct of missiles in outer spacewhere the creation of shock waves is not possible because of the lack ofatmosphere.

The invention comprises a method for directionally propellingprojectiles which consists in fitting one surface of a substantiallyflat metal plate which serves as the projectile over a correspondingsurface of a sheet of explosive and detonating the explosive to propelthe plate flatwise along a desired path with controlled accuracy.

If simultaneous destruction of two or more walls, such as the walls ofdual propellant tanks of a missile, is required, a metal plate isarranged on each side of the explosive and this arrangement positionedbetween the two walls so that upon detonation of the explosive the wallswill be substantially simultaneously ruptured with the two plates. Aprincipal feature of the invention is the selection of a metal, such as,lead or alloys containing at least ten percent lead which will notfracture or be prohibitively deformed by plastic deformation underimpulsive loading such as results when the explosive of anexplosive-metal interface is detonated. The accuracy of the projectileplate is, of course, achieved by selecting a flat plate which can bepropelled in a straight line.

The invention is best described by reference to the accompanying drawingin which like parts are represented by like numerals and in which,

FIG. 1 is a plan view of an assembled destruct device in which twocircular plates are used to form a wafer, one on each side of a sheet ofexplosive;

FIG. 2 is a cross sectional view on the line 2-2 of FIG. 1;

FIG. 3 is a cross sectional view of a destruct device in which only oneplate is used as the projectile;

FIG. 4 is a schematic showing of the destruct device of FIGS. 1 and 2arranged between propellant tanks, one containing oxidizer and the othercontaining fuel, the

. mixture of fuel and oxidizer forming a hypergolic mixture when mixed;and

FIG. 5 is a perspective view of a modification (schematic) of thedestruct device in which a rectangular shaped wafer is used, the casebeing omitted.

Referring to FIGS. 1 and 2, the self-destruct device 10 is illustratedwith the outer metal case 11 of aluminum bolted to the back 12 of thecase by means of bolts 13 or other suitable means.

Referring to FIG. 2, a sheet of explosive charge is represeated at 14sandwiched between two lead plates 16 and 18 to form a wafer destructcharge. Any conventional explo sive can be used, such as, TNT, PBX,composition A, PETN, or other type explosives. The material of the plateis critical for use of the device in the atmosphere and as discussedbelow must be one which responds properly when an explosive adjacent toits surface is detonated. Preferably, lead and alloys containing atleast ten percent lead are used as the metal must be one which will notfragment or become prohibitively deformed by the explosion beforetravelling an adequate distance. The outer case is not an essential partof the invention but merely serves as :9 a support to hold the leadplates securely against the face of the explosive before detonation ofthe explosive. Other equivalent means for accomplishing this canobviously be used. As will be seen, the mating surfaces of explosive andlead plates are flat, and the plate surfaces conform perfectly to thesurfaces of the explosive charge.

For detonating the explosive a detonator 20 of a conventional design isprovided with lead wires connected to an initiator not shown.

Reference is now made to FIG. 3 in which a modification of FIG. 2 isshown. In this modification a single lead plate 16 is used on one sideof the explosive charge 20, the assembly of explosive and plate beingsurrounded by case 11 in this modification. The detonator 20 in thisinstance is positioned centrally of the explosive charge on the sideopposite of the target, as shown.

FIG. 4 shows the destructor device illustrated in FIG. 2 positionedbetween two propellant tank domes 24 and 26 for simultaneous rupturingof the two domes. In this application the tanks will be rupturedsubstantially simultaneously by the metal plates on either side of theexplosive when the explosive is detonated.

In the modification of FIG. 5, the destruct device is constructed offlat lead rods and a flat rod of explosive, the length dimension beinglarge in relation to the width dimension. In this modification thethickness of the lead plate or slab is Ms" while that of the explosiveis /2", although these dimensions are not critical.

It is essential that the projectile plates be projected directionallyand with accuracy. This can only be accomplished if the mating surfacesof explosive and metal are flat and conform perfectly with nosubstantial voids in between. The amount of explosive used will ofcourse be a factor in the extent of impulsive loading to which the leadprojectile plates will be subjected. The size of the metal plates willalso be a factor in the operation of the destruct device.

The plates are preferably made of lead or alloys containing at leastabout 10% of lead. The metal which may be used for the material of theprojectile plates is one which will not fracture when the explosive ofthe metalexplosive interface is detonated. It has been found that whenthe metal plate is placed on top of the explosive as in themodifications described, plates of lead and alloys containing at leastten percent lead perform most satisfactorily. Other metals have agreater tendency to fracture and disintegrate before travelling throughthe atmosphere far enough to accomplish the purpose of the invention. Ithas been found that lead plates will travel up to ten feet withoutfracture or other deterioration provided they are flat. Surfaces whichare not flat will result in fracture of the plate. The operation of thedevice can be explained by reference to FIG. 4. In this application theselfdestruct device is arranged between two fuel and oxidizer tanks 24and 26 in a large missile, the fuel and oxidizer being hypergolic. Ifthe missile suddenly travels off course while in the atmosphere or inspace the explosive can be detonated automatically or by remote controlto propel the plates on either side of the explosive into the propellanttanks to rupture them and permit mixture of the hypergolic fluids.Contact of the fluids with each other results in a violent reaction orexplosion which destroys the missile.

It is to be understood that the self-destruct device is relatively smallin comparison with other parts of the missile, such as, the tanks, thisbeing one of the reasons for its use. Space and weight limitations onlarge missiles re quire the uEof a destruct device which is as mall andlight as possible.

The self-destruct device described has been tested extensively underconditions accurately simulating destruction of domes of propellanttanks and has proved to be entirely satisfactory. A self-destruct devicecomposed of PETN sheet explosive thick and a lead plate /s" in thicknessand 7 in diameter was positioned two feet from a dome 10 in diameterconstructed of aluminum alloy .062 in thickness. Upon detonation of theexplosive complete destruction of the dome resulted.

In another application a destruct device comprised of a PETN explosivesheet /2 thick sandwiched between lead plates A2" thick and 7 indiameter was mounted in the center of a reinforced propellant tank 10 indiameter and detonated, with complete destruction of the tank. Numeroustests similar to the above have been equally successful. The device isnow being used in large missiles.

The invention has been described by its application to a destruct devicefor simultaneously destructing opposing walls of missile fuel tanks.limited to its application in a destruct device as this application isfor the purposes of illustration only. The invention may be used in asingle projectile device as that shown in FIG. 3 for various purposes.It finds use in any application wherein it is necessary or advantageousto propel a projectile without the use of a projectile chamber. It isthus seen to have many applications in space vehicles and missilestraveling in the atmosphere, or in outer space wherein conventionalexplosives cannot be used to effect damage by traveling shock waves.

The invention has been illustrated with the use of plates of lead andalloys containing at least ten percent lead as projectiles in theatmosphere. Other metals may be used, particularly, outside theatmosphere.

It is therefore to be understood that various modifications and changesmay be made in the construction and arrangement of parts of the presentinvention without departing from the spirit and scope thereof as definedby the appended claims.

While the term plate has been used herein to describe the metalprojectile this is not to be considered as restricting the shape of theprojectile as practically any shape of projectile can be used, the mainrequirement being that the adjacent surfaces of explosive and projectileconform and be substantially flat in the preferred modification.

What is claimed is:

1. The method of substantially simultaneously rupturing a plurality ofwalls which comprises positioning a fiat plate of a material from theclass consisting of lead and alloys containing at least ten percent leadin front of each wall with one face of each plate facing a wall and theother face of said plate contiguous to and conforming to a face of anexplosive charge, and detonating said explosive charge to simultaneouslyand directionally propel said plates fiat-wise against said walls torupture them.

2. The method of simultaneously rupturing spaced apart walls of two fueltanks to release therefrom fluids to be mixed, which comprises: placinga piece of explosive material having at least two flat opposed parallelfaces between said spaced apart walls of said tanks and spaced apartfrom said tanks with each of said faces facing a corresponding one ofsaid walls; supporting a flat plate contiguous to each of said opposedfaces, each plate conforming precisely to the corresponding face ofexplosive and being of a material from the class consisting of lead andalloys containing at least ten percent lead; and detonating saidexplosive; whereby each of said plates is propelled flat-wise anddirectionally against the wall it faces to shatter it and thereby permitmixing of said fuels.

3. The method of simultaneously rupturing a plurality of walls whichcomprises: supporting a piece of explosive material having a flat facecorresponding to each of said walls in a position such that each face isfacing a wall to be ruptured; supporting a fiat plate of metallicmaterial contiguous to each face, each of said plates conformingprecisely to the corresponding face of explosive and being of a materialfrom the class consisting of lead and alloys containing at least tenpercent lead; and detonating said explosive; whereby each of said platesis propelled flatwise and directionally against the wall it faces torupture it.

4. The method of claim 3 in which the said fiat surfaces of saidexplosive charge are parallel.

Obviously, it is by no means 5. The method of rupturing a Wall of a bodywhich cornprises supporting a flat plate having frontal surfacedimensions greater than its thickness of a material from the classconsisting of lead and alloys containing at least ten percent of lead infront of said Wall with one face of the plate facing a Wall and in linetherewith and the other face of said plate contiguous to and conformingto a Wall of an explosive charge; and detonating said explosive chargeto propel said plate directionally against said wall to rupture it.

References Cited by the Examiner UNITED STATES PATENTS 2,494,256 1/50Muskat et al l0220 7/52 Cook 10256 3/55 MacLeod l02l 1/58 Dill 89-1 5/60 Howard et al. 2022-4 X OThER REFERENCES Claude Pernelle: ScientificAmerican Supplement No.

Explosive, Expansive anc Perforating Nov. 23, 1918, page 332 relied onvExaminers.

1. THE METHOD OF SUBSTANTIALLY SIMULTANEOUSLY RUPTURING A PLURALITY OFWALLS WHICH COMPRISES POSITIONING A FLAT PLATE OF A MATERIAL FROM THECLASS CONSISTING OF LEAD AND ALLOYS CONTAINING AT LEAST TEN PERCENT LEADINFRONT OF EACH WALL WITH ONE FACE OF EACH PLATE FACING A WALL AND THEOTHER FACE OF SAID PLATE CONTIGUOUS TO AND CONFORMING TO A FACE OF ANEXPLOSIVE CHARGE, AND DETONATING SAID EXPLOSIVE CHARGE TO SIMULTANEOUSLYAND DIRECTIONALLY PROPEL SAID PLATES FLAT-WISE AGAINST SAID WALLS TORUPTURE THEM.